i had a contract with a telecom company. i had to close my business cause it was make enough money anymore so i let the telecom company know and they sent me a final bill which got paid. Then a few months later after all paper work is done and business closed a lawyer representing them calls me and says i owe a balance of $2,000 that was on a revised final bill that was sent out.

The business was located in florida and was a llc can they put that on my credit or hold me responsible for that cause i signed the contract on behalf of my company?

A key part of the definition of an LLC is that the owners are not liable for the debt of the LLC. If the telecom bill was solely the obligation of the LLC, you should not be liable.

Keep in mind that in many cases creditors ask for personal guarantees before they extend credit to any small business. For example, credit card companies that issue "company cards" to a business are almost always doing so based upon the personal signature of the individual, not the business. Likewise, landlords often require the business owners to personally guarantee the company's lease.

If you did personally guarantee the payment somewhere in all the paperwork you signed to get the telecom service, then that is not protected by the LLC's statutory protection.